Spondylolisthesis is a medical condition in which one vertebra slips forward in relation to an adjacent vertebra usually in the lumbar region of the spine. This condition can cause symptoms that include pain in the low back, thighs, and/or legs, muscle spasms, weakness, and/or tight hamstring muscles while in some cases only radiographic imaging reveals the condition.
To correct this condition and other similar conditions of vertebral dislocation, the only effective long-term curative treatment is reconstructive surgery and fusion of the affected vertebra to its adjacent neighbor. Vertebral fusion is generally accomplished by fixing apparatus to and between vertebrae. In addition to the stabilization and correction of spondylolisthesis, other spinal conditions may be: stabilization of fractures, correction of spinal deformities (e.g. scoliosis, kyphosis), stabilization and correction of degenerative spinal lesions and narrow spinal canal, reconstruction after tumor resection, and secondary spinal surgery.
The novel method and implant discussed herein allows for the correction of spondylolisthesis by movement of the vertebrae into better alignment while maintaining stabilization of the vertebrae in the new position in order for the spinal fusion to be completed by ossification. Specifically, the implant is used to move the vertebrae into a post-surgical position and keep the vertebrae in the post-surgical position during the ossification process.
Roggenbuck in U.S. Pat. No. 6,491,695 discloses the use of an apparatus and method for aligning vertebrae which involves creating a helical threaded surface in endcaps of the vertebrae and then threading a positioning device into position to align the vertebrae. Once the vertebrae are positioned, the positioning device is removed and an implant is inserted to maintain the vertebrae in position.
Ray in U.S. Pat. No. 6,582,431 discloses the use of an expandable non-threaded spinal fusion device which requires the vertebrae to be moved into correct position before the device can be inserted and implanted.
Betz in U.S. Pat. No. 6,533,791 discloses a device for stabilization of the lumbar spinal column which requires cutting helical thread marks into the vertebrae that are to be repositioned and then installing an implant to maintain the position. The repositioning device does not stay in the body after the surgery but instead an implant must be inserted to maintain the repositioning.
Therefore, there is a need in the art to combine an implant with a repositioning device in order to reduce the possible repositioning of the vertebrae. There is a further need in the art to provide for adjustment of the vertebrae after an implant has been installed.